Molecular cloning and characterisation of a human brain A1 adenosine receptor cDNA

Using the sequence conservation in the G protein-coupled receptor superfamily, we have isolated an adenosine A1 receptor cDNA from a human hippocampal cDNA library by homology screening. When expressed in mammalian CHO.K1 cells, the protein encoded by this cDNA binds the A1-specific antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) with high affinity (Kd = 0.56 +/- 0.11 nM) and, functionally, is able to inhibit cAMP production upon receptor activation with the A1-specific agonist N6-cyclopentyladenosine (CPA) (> 80% inhibition at 10(-7) M CPA). The binding and functional characteristics of the expressed cDNA demonstrate that we have isolated a human brain adenosine receptor cDNA of the A1 subtype.